A Highly Sensitive Spectrophotometric Assay of Bleomycins Based on the Fading Reaction of Some Halofluorescein Dyes

In weak acidic medium, anticancer antibiotics bleomycin A5 （BLMA5） and bleomycin A2 （BLMA2） can react with halofluorescein dyes such as erythrosin （Ery）, eosin Y （EY）, eosin B （EB） and rose bengal （RB） by virtue of electrostatic attraction and hydrophobic force to form the ion-association complexes, which can result in the fading reactions of four halofluorescein dyes. The maximum fading wavelengths of these four dyes were located at 527 nm for Ery, 515 nm for EY, 517 nm for EB and 546 nm for RB, respectively. The decrements of absorbance （AA） were directly proportional to the concentrations of bleomycin in a certain range. A new method for the determination of bleomycins anticancer drugs based on fading reactions of halofluorescein dyes has been developed. The method was not only highly sensitive but also simple and rapid. The molar absorptivities （ε） ranged from 1.5 × 10^5 to 7.5 × 10^5 L·mol^-1·cm^-1. It was applied to determination of the bleomycins in human serum, urine and rabbit serum samples. In this work, the spectral properties and the optimum reaction conditions were investigated. The structure of ion-association complexes and the reaction mechanism were discussed.     

From D-glucose to biologically potent L-hexose derivatives: synthesis of alpha-L-iduronidase fluorogenic detector and the disaccharide moieties of bleomycin A2 and heparan sulfate

A novel and convenient route for the synthesis of biologically potent and rare L-hexose derivatives from D-glucose is described. Conversion of diacetone-alpha-D-glucose (14) into 1,2:3,5-di-O-isopropylidene-beta-L-idofuranose (19) was efficiently carried out in two steps. Orthogonal isopropylidene rearrangement of compound 19 led to 1,2:5,6-di-O-isopropylidene-beta-L-idofuranose (27), which underwent regioselective epimerization at the C3 position to give the L-talo- and 3-functionalized L-idofuranosyl derivatives. Hydrolysis of compound 19 under acidic conditions furnished 1,6-anhydro-beta-L-idopyranose (35) in excellent yield, which was successfully transformed into the corresponding L-allo, L-altro, L-gulo, and L-ido derivatives via regioselective benzylation, benzoylation, triflation and nucleophilic substitution as the key steps. Applications of these 1,6-anhydro-beta-L-hexopyranoses as valuable building blocks to the syntheses of 4-methylcoumarin-7-yl-alpha-L-iduronic acid and the disaccharide moieties of bleomycin A(2) as well as heparan sulfate are highlighted.     

Site-specific modification of the 5"-terminal fragment of PGY1/MDR1 gene mRNA by reactive conjugates of antisense oligonucleotides

The site-specific modification of the 5"-terminal fragment of PGY1/MDR1 mRNA by oligodeoxyribonucleotide conjugates bearing residues of bleomycin A₅ (Blm), cobalt(ii) tetracarboxyphthalocyanine (Phcn), 4-[N-(2-chloroethyl)-N-methylamino]benzylamine (RCl), or perfluoroarylazide (Az) was studied. Conjugates of oligonucleotides complementary to the RNA sequences 123—138 and 155—166 selectively modify RNA in the vicinity of these regions. The highest efficacy (up to 50%) was achieved in reactions with alkylating and perfluoroarylazide conjugates of oligonucleotides. Conjugates of perfluoroarylazide with 2"-O-modified oligonucleotides are much more efficient than analogous conjugates with oligodeoxyribonucleotides (extents of RNA modification are 40—50% and 20%, respectively).     

博莱霉素切割DNA反应的定量测定及其影响因素

用硫代巴比妥酸反应分析了博莱霉素 Ａ５ （ Ｂ Ｌ Ｍ Ａ５ ）对 Ｄ Ｎ Ａ 的断裂作用在 Ｆｅ２＋ 和 Ｏ２存在下, Ｂ Ｌ Ｍ Ａ５能导致 Ｄ Ｎ Ａ 链断裂研究了一些因素对 Ｂ Ｌ Ｍ Ａ５ 催化 Ｄ Ｎ Ａ 断链反应的影响,设计并建立了 Ｂ Ｌ Ｍ Ａ５ 切割 Ｄ Ｎ Ａ 反应的定量测定方法,并测得 Ｋｍ 约为１５３ μｍ ｏｌ· Ｌ－ １, Ｖｍ ａｘ 约为００４６ Ａ５３２ｎｍ Ｕｎｉｔ·ｓ－ １      

Carbon—Hydrogen Bonds of DNA Sugar Units as Targets for Chemical Nucleases and Drugs

This review article focuses on the molecular aspects of DNA cleavage by synthetic chemical nucleases (transition metal complexes endowed with redox properties and DNA affinity) and natural drugs (cytotoxic agents such as bleomycins or enediynes). Unlike deoxyribonucleases, which catalyze the nucleophilic attack of water on the phosphorus atom of a particular phosphodiester entity, these nonhydrolytic DNA-cleavers are able to oxidize the sugar units, generally by hydrogen atom abstraction. Examples of oxidative attack on each of the five different C? H bonds of deoxyribose are known, depending on the nature, structure, type of activation, or mode of DNA interaction of the DNA-cleaver. Further evolution at the site of the initial lesion leads to the release of bases, oxidized deoxyribose units, or oxidized sugar fragments appended to the base or the terminal phosphate. In most cases the loss of a part (at least) of a nucleoside, with the concomitant loss of one base information, primarily induces the cleavage of the DNA strand. For both types of DNA cleavage reagents studied within the two last decades, the modes of activation and DNA binding are presented, as well as the details on the mechanism of deoxyribose oxidative degration. Because of the need for highly efficient and highly specific reagents, the development of new artificial and selective DNA cleavers, supported by an improved knowledge of these different mechanisms of DNA cleavage, is to-day a challenging area in the rational design of antitumoral or antiviral agents, as well as in the field of molecular biology.     

Syntheses, structures and reactivities of designed analogues of cobalt(III)- bleomycinsz : Insight into the mechanism of sequence-specific DNA cleavage upon illumination

Three Co (III) complexes of a designed ligand PMAH that mimics the metal-binding domain of the antitumor antibioticbleomycin (BLM) have been isolated and structurally characterized. The coordination structures of the various forms of Co(III)-BLMs have been established on the basis of spectral similarities between these synthetic analogues and the corresponding Co(III)-BLMs. All three analogues, like Co(III)-BLMs, induce DNA strand scission upon UV illumination. Both DNA cleavage and spin trapping experiments demonstrate that UV irradiation of the analogues generates a C/N-based radical on the ligand framework which rapidly reacts with water to produce -OH radical near the DNA helix and causes strand scission. A similar mechanism could account for the photoactivity of the Co(III)-BLMs. Covalent attachment of DNA-binding groups to these analogues enhances the DNA-affinities and photocleavage efficiencies to a great extent. The hybrid analogues promote sequence-specific DNA photodamage at micromolar concentrations. The metallated cores of the hybrid analogues are the primary determinant of the observed sequence-specificity. Details of the mode of binding of the hybrid analogues to DNA have been explored by NMR techniques.     

Directed cleavage of RNA within an imperfect complementary complex by oligonucleotide—bleomycin A5 conjugates

It was demonstarted for the first time that RNA can be subjected to site-specific oxidative cleavage induced by the glycopeptide antibiotic bleomycin A₅ (Blm) covalently linked to the 3"-terminus of an oligodeoxyribonucleotide through two, three, or four residues of hexaethylene glycol phosphate (p-heg) _n . The oligonucleotide conjugate with bleomycin forms an imperfect complementary complex with the RNA to be cleaved (5"-prCGGAGUUGGAAAACAAUGAAAAGGCCCCCA/Blm-(p-heg) _n -3"-pdGCCTCACCTTTTGTTA). The cleavage occurs at the only nucleotide residue (U) preceding a one-nucleotide bulge in the RNA chain, which is formed due to imperfect complementarity between the oligodeoxyribonucleotide and the RNA to be cleaved.     

Comparative proteome profiling of bleomycin‐induced lung toxicity in rats by 2D–nano‐LC–MS/MS and spectral counting

The mechanisms involved in bleomycin‐induced lung toxicity have not been fully understood to date. This work aimed to compare the proteome profiling of bleomycin‐induced lung toxicity by using 2D–nano‐LC–MS/MS and spectral counting. By comparing the spectral counts of identified proteins between control and bleomycin‐treated groups, we noted that 102 proteins were upregulated and 28 proteins were downregulated in the bleomycin‐treated group. Among these differently expressed proteins, five proteins were chosen for validation by Western blot analysis. The levels of these five proteins were consistent with proteomic results. These potential mediators can facilitate the translation of the underlying mechanisms of bleomycin‐induced lung toxicity to molecular targets in the clinical arena.